Generated class can't be used for deserialization

[Yotamho]

I have a Message case class compiled by avrohugger,
I saved some serialized Messages in a file (using a scala version of the avro example),
Now I try to deserialize the Message objects in the file:

def readMessages(file: File): Vector[Message] = {
  val reader = new SpecificDatumReader[Message](classOf[Message])
  val dataFileReader = new DataFileReader(file, reader)
  val result = Iterator.continually(dataFileReader.next).takeWhile(_ != null).toVector
  dataFileReader.close()
  result
}

Line 3 in the following code fails on org.apache.avro.AvroRuntimeException: Not a Specific class: class com.xxx.protogate.generatedsources.Message.
Checking on SpecificData makes a lot of sense, as the createSchema method uses reflection to get the declared "field" SCHEMA$, but this is a method in the avrohugger's compiled object, so AFAIU it will never work this way.
Is there any way to work around it for now?

Exception stack trace:

An exception or error caused a run to abort: avro.shaded.com.google.common.util.concurrent.UncheckedExecutionException: org.apache.avro.AvroRuntimeException: Not a Specific class: class com.elbitsystems.protogate.generatedsources.Message 
org.apache.avro.AvroRuntimeException: avro.shaded.com.google.common.util.concurrent.UncheckedExecutionException: org.apache.avro.AvroRuntimeException: Not a Specific class: class com.elbitsystems.protogate.generatedsources.Message
	at org.apache.avro.specific.SpecificData.getSchema(SpecificData.java:227)
	at org.apache.avro.specific.SpecificDatumReader.<init>(SpecificDatumReader.java:37)
	at com.elbitsystems.protogate.TestUtils$.readMessages(TestUtils.scala:39)
	at com.elbitsystems.protogate.AppTest.<init>(AppTest.scala:17)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance0(Native Method)
	at sun.reflect.NativeConstructorAccessorImpl.newInstance(NativeConstructorAccessorImpl.java:62)
	at sun.reflect.DelegatingConstructorAccessorImpl.newInstance(DelegatingConstructorAccessorImpl.java:45)
	at java.lang.reflect.Constructor.newInstance(Constructor.java:423)
	at java.lang.Class.newInstance(Class.java:442)
	at org.scalatest.tools.Runner$.genSuiteConfig(Runner.scala:1428)
	at org.scalatest.tools.Runner$.$anonfun$doRunRunRunDaDoRunRun$8(Runner.scala:1236)
	at scala.collection.immutable.List.map(List.scala:287)
	at org.scalatest.tools.Runner$.doRunRunRunDaDoRunRun(Runner.scala:1235)
	at org.scalatest.tools.Runner$.$anonfun$runOptionallyWithPassFailReporter$24(Runner.scala:1031)
	at org.scalatest.tools.Runner$.$anonfun$runOptionallyWithPassFailReporter$24$adapted(Runner.scala:1010)
	at org.scalatest.tools.Runner$.withClassLoaderAndDispatchReporter(Runner.scala:1506)
	at org.scalatest.tools.Runner$.runOptionallyWithPassFailReporter(Runner.scala:1010)
	at org.scalatest.tools.Runner$.run(Runner.scala:850)
	at org.scalatest.tools.Runner.run(Runner.scala)
	at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.runScalaTest2(ScalaTestRunner.java:131)
	at org.jetbrains.plugins.scala.testingSupport.scalaTest.ScalaTestRunner.main(ScalaTestRunner.java:28)
Caused by: avro.shaded.com.google.common.util.concurrent.UncheckedExecutionException: org.apache.avro.AvroRuntimeException: Not a Specific class: class com.elbitsystems.protogate.generatedsources.Message
	at avro.shaded.com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2234)
	at avro.shaded.com.google.common.cache.LocalCache.get(LocalCache.java:3965)
	at avro.shaded.com.google.common.cache.LocalCache.getOrLoad(LocalCache.java:3969)
	at avro.shaded.com.google.common.cache.LocalCache$LocalManualCache.get(LocalCache.java:4829)
	at org.apache.avro.specific.SpecificData.getSchema(SpecificData.java:225)
	... 20 more
Caused by: org.apache.avro.AvroRuntimeException: Not a Specific class: class com.elbitsystems.protogate.generatedsources.Message
	at org.apache.avro.specific.SpecificData.createSchema(SpecificData.java:285)
	at org.apache.avro.specific.SpecificData$2.load(SpecificData.java:218)
	at org.apache.avro.specific.SpecificData$2.load(SpecificData.java:215)
	at avro.shaded.com.google.common.cache.LocalCache$LoadingValueReference.loadFuture(LocalCache.java:3568)
	at avro.shaded.com.google.common.cache.LocalCache$Segment.loadSync(LocalCache.java:2350)
	at avro.shaded.com.google.common.cache.LocalCache$Segment.lockedGetOrLoad(LocalCache.java:2313)
	at avro.shaded.com.google.common.cache.LocalCache$Segment.get(LocalCache.java:2228)
	... 24 more

[julianpeeters]

Scala's fields can't be reflected by Java reflection, regardless of where SCHEMA$ is defined. Luckily there are other constructors we can use that will take a schema directly and preempt reflection: https://github.com/apache/avro/blob/fab3d4051c6bf5cacf6bd80895a72332ae5f362f/lang/java/avro/src/main/java/org/apache/avro/specific/SpecificDatumWriter.java#L38

Since avrohugger just generates the classes, how those classes are used is up to the user. You can find further examples in the scripted serialization tests, e.g.: https://github.com/apache/avro/blob/fab3d4051c6bf5cacf6bd80895a72332ae5f362f/lang/java/avro/src/main/java/org/apache/avro/specific/SpecificDatumWriter.java#L38

Thanks for letting me know the trouble you ran into. Please try those examples and reopen if you are still experiencing issues.